A secondary means of recovering hydrocarbons from an oil or gas field is to inject water into the subterranean reservoir to maintain reservoir pressure and to drive certain fractions of the hydrocarbons to producing wells. Water flooding operations require in general, a sufficient supply of water for injection; means for treating the source water to meet the reservoir conditions; a pump system; and access to the formation via a wellbore. In land based operations the source of the water is commonly from fluid produced from the subject reservoir; water treatment facilities can be readily constructed and accessed; and traditional pumping equipment is readily available. Water flooding conducted in marine operations presents drawbacks that can preclude the use of water flooding to obtain currently available hydrocarbon reserves.
Marine operations, being those in which the wellbore is below a water body and access to the wellbore is primarily via a platform or water craft, present logistical and economic limitations. In current offshore or marine water flood operations the water source is often produced well water that is processed and boosted via the platform facilities to attain the required injection pressure. Occasionally seawater is recovered, treated and then injected into the well from a platform.
Most producing fields involve numerous spaced apart wells and the injection wells are often positioned on the perimeter of the reservoir. Thus, the injections wells are typically positioned well away from the field pumping facilities requiring that utilization of centralized injections platforms connected to the various injection wells via submarine pipelines. It is therefore a desire to provide a pumping system that may be positioned at a point of need, below the surface of a body of water, for the purposes such as, without limitation, injecting raw seawater into one or more subterranean wells, producing a fluid from a wellbore, propelling a pig for pigging pipelines or dewatering flooded pipelines